Breakdown testing apparatus



-Aug.. 9, 1949. v. MICHAL BREAKDOWN TESTING APPARATUS Filed Jan. 7, 19442 sheets-sheet 1 M/l/FA MR i. M M/CWAL By /AM K W ATTO/PA/fy 1949. v.MICHAL BREAKDOWN TESTING APPARATUS 2 Sheets-Sheet 2 Filed Jan. 7, 1944Patented Aug. 9, 1949 TESTING APPARATUS Loon: V. Michal, Chicago,Ill.,.a,ssignoi: to Western; Electric Company, Incorporated; New York.N..Y.,,.a corporation of New York Application January 7, 1944;.Serial1Nm75352 4 claims. (Cl. 115-183) This: invention. reiatos to: breakdown.testing apparatus, and; more: pantimrlarly' to; apparatus fordielectric: laminations fin? breakdown.

In isam obziect ofi the: present. invention: to pro:-- vidn a; simpleand accurate apparatus, for rapidly making, breakdown tests,

In accordance: with. one embodiment: of the: inmention: an; appiiedi to;the: of! a breakdown test: on mica; larninavtionshaving: silver sheetsapplied to-opnnsite: faces: thereof, a: plurality of laminationsiplaced: inv a; rack or cradle; which may then be slipped into a testingfixtureshaving spring-r contacts to bieam against: a: conducting member:commonitotall; emigrant-merits dmtherack or; cradles Afiter'ttm rack:cradiezhasz beam thus positionen in the: fixture, ahingedtbraokeh supnorm or number-'01; noun; lamps onion-1- in number to; the number ofcompartments the cradle mar; be: rushed to cazrm spring contactsfi'HgBIS innividuaiz to; that lamps into contact with; a2 surfia'oe 01fthe laminwtionsi The: neon; lamps: are coruzrecteddnpaxaiini:1703-13119: output an a: higirvo1trig-e transformer amt; are: each in.senias with av relatively nesisfianc g. Hart: of which shunted bythe-nnmlmnwhenehyrwhmmbreab dimn occurs. in: one of the its associntedlamps wiiia bot will notinterfere with the other test circuits:11315311211 with;

comnleize understanding: ot the: invention had by? reference to thefioiinwing dataiiem die:-

scription when cons-inched? in. conjunction; with the am drawings,wherem 11 at sidn eiemtionak view 05 apparatus". comprising. at.plfdfiiiflifidl embodiment of: the; in.- ircirtiom the cradie: or rank:and: ar tn be tested. being shown, out of. the: apparatus pmto theiriJHSEItiQIL 2 is: a. transverse; vertical sectional: View on amerdamgedscnlestazkem thmughzthe apparatus;

Bin. 3 is diagram tbs manner in which the various parts of theelectrical-amaze trains are: interconnected;

Fig.3 4- is or vertical: sectimral; View takemsnbsiam fliarl-lw the 4-4or. Eiga. 2: in the. dimention of: the; arrows; and.

Fig. 5' is a plan sectional view taken substantiarliy, along the line5-5 ofi 2 im the: direction 015 thee arrows.

In the: drawings, as illustrated in Figs. 1,, 2, 4 and! 5 2,; fixture isprovided comprising a base. tit having: side; members H. and 12': ands8; back plate i3. linterposed betweenthe side. members is, a coverpia-te: i=4 which; extends: between: thaside memhersr in; az horicontaiiplane and: abuts a rounded transparent plastic case front. ii;

which: is- 83.150- mounted. between. the, side: members and. which: itsbottomand resting on at cross bar LEE. In addition to-thecrossharl.ti,.there is a; @rossbar: L-t spaced from; the. cross, bar I61- andextending: between the side members, H and. 1'2, and: intermediate: the;cross bars L6. and: H. are. slots t8, and 1-5,. which: are,- formed; in.the. side memher-s lit and i=2; respectivzely,,to-receivenrack on cradledesignated generally by thenumeral 2D to; hold mica laminations 2| inposition to be tester-t: inthe apparatus. Extending between the.sidememhers I l and l2. is; a. block- I-ZJ, of; insulating material:having at parinofo contact springs 2 2: and- 23; mounted on: it forcontacting with a: portion of the rack 20.

The iaminations to.- be tested in the apparatus comprise; strips or,mica Z'L, on. opposite. surfaces: at which... silver. sheets or plates24 and-V25. have; been fixed. These laminations are placed on whiie the;rack; is out oi the.v testing fixture; midi a1 groups of: the laminations may thus, be: fiestedtsiinultaneouslm by: inserting: the rack holdingthem; in the; appatrazlnzs.

Extending across: the base; Iii: between the side members: ME and t2;is. or support-block.- 311? having a; switch his of the hype known as a.microswitch mount-ow upon its. front face. Thesup? port block 3!! has ahinge 3:2 attachedto; it and to:- a mounting block 33! made offinsulating martea-nd-supporting' a; plurality ofneon lamps 34'. In:addition tosupportingthe neon lamps- 34, the mounting block 33carries aseries ofleafsprings 35, of whiohthere is provided one for each1ami'nation supporting section of the rank 2!). These Ieaf springs areconnectedto theneon lamps (N and constitute contact memb as forinterconnecti'ng the'upper siiver sheet or-pl'ate- 2 i and the'lamp 3'4in the ciicuit during the testing of the, lamina.- tions. The switch 3!serves. to close themain switch of the testing circuit when themounting; bTock 23 is rocked to the, positionshown in Fig, 2; whichmovement will.v carry the contact springs into engagement with. the.laminations and close the switch; 31-. The, mounting. block 3.3 is.provided with a pair: of handles 35. which extend through arcuaite slots3FE3J. formed in. the side members it and [-2 to permit the rockin oithe mounting, plate: 3-2 and parts carried thereby from the;positionshowninliig. 1 to-the position shown Fig; 2;, Any suitable;means, may be provided tor either: urging the mounting block 33 to-the,position shown Fig. 1, or for resisting. move ment of the; handles 3%throughout; their entire monuments so, that, the handles. may be movedto to the testing apparatus upon the closure of the switch 3|.

The rack or cradle comprises a main,block,

nations from slipping off the back end of the rack. A series of slots41-41 are formed in the block 45 to receive spacers 48, which are heldin place on the main block 45 by means of pins 49 inserted in theapertures in the spacers 48 and resting against the bottoms of slots 50and 5|, which extend longitudinally of the main block 45.

In the preferred embodiment of the invention, there are tenlamination-receiving sections formed on the rack and, therefore, thereare H slots 4'1 cut in the block. To conserve space, only five of thesections have been shown and the figures of the drawing have been brokenthrough the middle to indicate the fact that a number of positions areomitted. Any suitable number of laminations may be tested at one time,but it has been found advisable to test just ten of them at a time.

The main block 45 has a series of contact members55mounted thereon.These contact members comprise a head portion 56, as shown most clearlyin Fig. 2, and a shank '51, which is threaded to receive a machine screw58. The machine screws 55 are seated in a conductor plate 59, whichextends across beneath all of the lamination supporting sections of therack and when the rack is positioned in the apparatus, the conductorplate will rest upon the contact springs 22 and 23, thus to connect thesilver plate 25 on the lamination 2| in each section of the rack withthe testing circuit.

As shown in Fig. 3, the laminations 2| to be tested will thus beconnected in parallel across a circuit from a transformer 62, which issupplied with power from 115 volt A. C. source t3 upon closure of theswitch 3| and which will apply a thousand volts through an adjustableresistance 64 and a condenser 65 to the parallel circuits in which thelaminations 2| are connected by means of the contact springs 22 and 23and contact springs 35. Each of the circuits leading from the contactsprings 35 is connected directly to one of the neon lamps 34 and thencethrough a 90,000 ohm resistor 66 and back to the output side of thetransformer 62. Connected in series with each of the 90,000 ohmresistances is a 10,000 ohm resistance 61 and the neon lamp is connectedin shunt across the 10,000 ohm resistance. In the operation of theapparatus, ten laminations 2! having silver plated sheets, as shown at24 and 25, may be placed on the rack and the rack may then be slid inposition as shown in Fig. 2, where each lamination to be tested will bealigned with the contact spring fixed on the support block 33. Thehandles 36 may then be moved from the position shown in Fig. l to theposition shown in Fig. 2. When the handles are thus moved to operativeposition, the switch 4 3| will be closed to supply power to the testingcircuit and since the neon lamp 40 is connected across the I I0 voltsource 63, closure of the switch 31 will complete the circuit to lamp toindicate that power is being supplied through the transformer 62 to theunderside of all of the laminations 2! which have their silver plate 25in engagement with one of the contact members 55. The breakdown circuitacross the laminations will be completed by the contacting of thecontact springs 35 with the plate 24 on the upper surface of thelaminations and if none of the laminations break down under the test,none of the lamps 34 will be lighted. However, if one of the laminationsbeing tested breaks down upon the application thereto of the 1000 volttesting current, its

associatedneon lamp 34 will be lighted. The

lighting of a neon lamp 34 due to the breaking down of the laminationzlassociated therewith will not disturb the test circuits to otherlaminations being tested simultaneously, due to the fact that the neonlamp'34 is connected in shunt across a 10,000 ohm resistance which is,together with the lamp 34, in series with the 90,000 ohm resistanceindividual to it. In this manner, the application of the test to thoselaminations which are satisfactory will not be interfered with by thebreaking down of one of the laminations since the total current of allthe parallel circuits at breakdown will not be great enough to reducethe voltage belowthe minimum desired.

What is claimed is:

In a breakdown-testing apparatus, a rack for holding a pluralityofspecimens to be tested, a fixture for receiving said rack, means on saidrack for contacting one side of each of the specimens, a hinged frame, aplurality of neon lamps on said frame, contact fingers on said frame forinterconnecting the specimens separately in series with the lamps, aresistance in series with each of said lamps,resistances individual toand in shunt with said lamps, and means for connecting said means onsaid rack and said resistances to a-source of high potential to supply ahigh voltage to all of the specimens.

2. In a breakdown testing apparatus, a rack for holding a plurality ofspecimens to be tested, a fixturefor receiving said rack, means on saidrack for contacting one side of each of the specimens, a hinged frame, aplurality of neon lamps on said frame, contact fingers on said frame forinterconnecting the specimens separately in series with the lamps, aresistance in series with each of said lamps, resistances individual toand in shunt with said lamps, means for actuating the hinged frame toengage all of the contact fingers simultaneously with their associatedspecimens and means for'connecting said means on said rack and saidresistances to a source of high potential for supplying a high voltageto all of the specimens.

3. In a breakdown testing apparatus, a rack for holding a plurality ofspecimens to be tested, a fixture for receiving said rack, means on saidrack for contacting one side of each of the specimens, a hinged frame, aplurality of neon lamps on said frame, contact fingers on said frame forinterconnecting the specimens separately in series with the lamps, aresistance in series with each of said lamps, resistances individual toand in shunt with said lamps, and a source of power connectible tosupply current in parallel to all of the specimens through the meanscontacting one side of the specimen and through the contact fingers.

4. In a breakdown testing apparatus, a rack for holding a plurality ofspecimens to be tested, a fixture for receiving said rack, means on saidrack for contacting one side of each of the specimens, a hinged frame, aplurality of neon lamps on said frame, contact fingers on said frame forinterconnecting the specimens separately in series with the lamps, aresistance in series with each of said lamps, resistances individual toand in shunt with said lamps, a source of power connectible to supplycurrent in parallel to all of the specimens through the means contactingone side of the specimen and through the contact fingers, and a switchoperable by the hinged frame for closing the circuit to the powersource.

LEON V. MICHAL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

